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  Aluminum-free borosilicate glass and applications thereofUSPTO Application #: 20070004580Title: Aluminum-free borosilicate glass and applications thereof Abstract: The fluorescent lamp is made with an aluminum-free borosilicate glass having a composition, in percent by weight, based on oxide content of: SiO2, 65-77; B2O3, 7-20; Li2O, 0-2; Na2O, 0-4; K2O, 3-12; MgO, 0-2; CaO, 0-2; with MgO+CaO, 0-3; BaO, 0-3: ZnO, 0-2; ZrO2, 0.8-12; TiO2, 0-10; CeO2, 0-1; and F−, 0-0.6. Preferred embodiments with more than 1% by weight TiO2 have especially good UV blocking properties and are especially suitable for lamp glass for backlights. Other embodiments have good sealing properties to tungsten, KOVAR®, and molybdenum and have coefficients of thermal expansion α of 4.7 to 5.3×10−6/K, good chemical resistance, and a working point VA of between 990° C. and 1290° C. (end of abstract) Agent: Striker, Striker & Stenby - Huntington, NY, US Inventor: Christof Kass USPTO Applicaton #: 20070004580 - Class: 501065000 (USPTO) Related Patent Categories: Compositions: Ceramic, Ceramic Compositions, Glass Compositions, Compositions Containing Glass Other Than Those Wherein Glass Is A Bonding Agent, Or Glass Batch Forming Compositions, Silica Containing, 40 Percent - 90 Percent By Weight Silica, And Boron The Patent Description & Claims data below is from USPTO Patent Application 20070004580. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The invention relates to borosilicate glass and also to uses of the glass. [0003] 2. Description of the Related Art [0004] The group of the borosilicate glasses is extremely extensive. The representatives of this group have the following basic composition range in common: SiO.sub.2, approx. 70 to 80 percent by weight, B.sub.2O.sub.3, 7 to 20 percent by weight, Al.sub.2O.sub.3, 2 to 7 percent by weight, Alkali metal oxides, 3 to 10 percent by weight. [0005] The glasses contain aluminum oxide in order to improve their resistance to devitrification and the chemical resistance. [0006] However, glasses of this type release aluminum ions to a wetting aqueous liquid, which is disadvantageous for certain applications. For example, aluminum is currently suspected of harming the health of people of corresponding disposition. In such cases, therefore, conventional primary pharmaceutical packaging materials made from glass are relatively unsuitable for the administration of injectable substances. [0007] Furthermore, aluminum oxide increases the melting and working points of the glasses considerably, increasing the energy consumption involved in the production processes. [0008] The physical and glass-technical properties influenced by Al.sub.2O.sub.3 generally cannot be reproduced by simply replacing the aluminum oxide with one or more other constituents. Rather, completely new developments or extensive changes to the glass composition are required. [0009] Standard borosilicate glasses are distinguished by their high chemical stability and their high ability to withstand temperature changes. They have a low coefficient of thermal expansion. [0010] On account of these properties, they are used in particular as ampoules and vials in the pharmaceutical industry for packaging, for example, injection preparations, for apparatus and equipment used in the chemical industry, both in production and on a laboratory scale, or as lamp glasses. [0011] There is extensive patent literature concerning glasses of this type. [0012] For example, DE 42 30 607 C1 describes chemically highly resistant borosilicate glasses which can be fused to tungsten. According to the examples, the glasses have working points V.sub.A>1210.degree. C. [0013] The borosilicate glasses described in German Laid-Open Specification DE 37 22 130 A1 also have high working points. Although the glasses belong to the first hydrolytic glass, they are relatively susceptible to crystallization, on account of the absence of K.sub.2O in these glasses. [0014] The Li.sub.2O-containing glasses described in German Patent DE 195 36 708 C1 are also highly chemically stable but also have disadvantageously high working points. [0015] The glasses described in German Patent DE 44 30 710 C1 have a high SiO.sub.2, content, namely >75 percent by weight and >83 percent by weight of SiO.sub.2+B.sub.2O.sub.3 in combination with an SiO.sub.2/B.sub.2O.sub.3 weight ratio of >8, which means that they are chemically highly stable but also have excessively high working points. SUMMARY OF THE INVENTION [0016] Therefore, it is an object of the invention to find a glass, which satisfies the above-mentioned requirements imposed on previous borosilicate glasses, has favorable working points and is free of Al.sub.2O.sub.3. [0017] According to the invention the aluminum-free borosilicate glass has good chemical resistance and a composition, in percent by weight, based on oxide content, of: TABLE-US-00001 SiO.sub.2 60-78 B.sub.2O.sub.3 7-20 Li.sub.2O 0-2 Na.sub.2O 0-4 K.sub.2O 3-12 MgO 0-2 CaO 0-2 with MgO + CaO 0-3 BaO 0-3 ZnO 0-2 ZrO.sub.2 0.8-12 TiO.sub.2 0-10 CeO.sub.2 0-1 F.sup.- 0-0.6 and optionally at least one refining agent in a standard amount for refining. Continue reading... Full patent description for Aluminum-free borosilicate glass and applications thereof Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Aluminum-free borosilicate glass and applications thereof patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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